Electrolarynx control button arrangement with improved frequency control

ABSTRACT

An electrolarynx includes a case housing tone-producing circuitry, a power switch to turn on the circuitry, a control button (i.e., a pushbutton) to actuate the power switch, and a pressure-sensitive-resistor (PSR) that is physically coupled to the pushbutton. The tone-producing circuitry is configured to respond to variations in PSR resistance that are caused by a user depressing the pushbutton. User-selected modes, that are selectable in one embodiment with a mode switch, include multiple frequency-varying modes (FVMs) in which the frequency of the electrolarynx tone is varied with different sensitivities to variations in PSR resistance, and multiple volume-varying modes (VVMs) for varying the volume of the electrolarynx tone with different sensitivities. A preferred embodiment provides a nonlinear frequency characteristic that facilitates operation at the low end of the pushbutton-controlled (i.e., PSR-controlled) frequency range, accomplishing same by applying suitable shape factors to frequencies of a linear frequency characteristic.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of U.S. patent applicationSer. No. 15/043,516 filed Feb. 13, 2016 (i.e., the parent application),which parent application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/273,319 filed Dec. 30, 2015.

BACKGROUND OF THE INVENTION 1. Technical Field

This invention relates generally to the electromechanical speech aidscommonly referred to as artificial larynxes and as electrolarynxes, andmore particularly to an improved electrolarynx construction withincreased functionality.

2. Description of Related Art

A person without normal use of their vocal cords or larynx often uses anelectrolarynx to speak. The electrolarynx includes a sound-producingcomponent that delivers an electrolarynx tone (e.g., a buzzing sound)having a fundamental frequency in the speech range of the average humanvoice. To speak, the user introduces this artificially generated toneinto a resonant speech cavity (i.e., the mouth, nose, or pharynx). Whiledoing so, the user modulates the electrolarynx tone by varying the shapeof the resonant speech cavity and by making the usual tongue, teeth, andlip constrictions so as to articulate the modulated tone as humanspeech.

U.S. Pat. Nos. 5,812,681; 6,252,966; 9,031,249; and U.S. Pat. No.9,116,539 issued to Clifford J. Griffin describe some existingelectrolarynxes. Each of those electrolarynxes typically includes afour-inch to five-inch long case that houses an electronic circuitboard, a battery, an electro-mechanical transducer for producingvibrations (i.e., the electrolarynx tone), a volume control, and a powerswitch. The user grasps the case in one hand, actuates the power switchand volume control, and then presses the transducer portion of theelectrolarynx against the outside of their throat so that electrolarynxtone vibrations travel through the throat tissues and into the mouth andthroat for modulation and articulation.

One such electrolarynx includes a pressure-sensitive resistor (PSR)coupled to a pushbutton; the user depresses the pushbutton with theirthumb to actuate the power switch while varying the pressure on the PSR(often referred in the alternative as a force-sensitive resistor, orFSR). The PSR is connected to electronic circuitry that varies thefrequency of the electrolarynx tone according to changes in the amountof pressure (i.e., force) applied to the PSR. That way, thepushbutton-PSR combination enables both electrolarynx power-on andfrequency variation of the electrolarynx tone with minimal, unnoticeablemovement of the user pressing the pushbutton. Operation is somewhateasy, and a wide and continuous range of frequencies allows forincreased control and subtle voice inflection, includingsyllable-specific intonation which may be used to approximate regionallyspecific or country specific voice patterns. Nevertheless, variation ofelctrolarynx volume and careful frequency control at the low end of thepushbutton-controlled frequency range can be somewhat challenging.

SUMMARY OF THE INVENTION

In view of the foregoing, it is a primary objective of the presentinvention to provide an electrolarynx having significant improvementsand increase functionality, including ease of both frequency and volumevariation and ease of frequency control at the low end of thepushbutton-controlled frequency range. The “mode switch aspect” of thepresent invention helps achieve the above objective by providing anelectrolarynx that enables a user to select which electrolarynx toneattribute is affected by variations in the resistance of the PSR. Theuser simply operates a mode switch on the electrolarynx to select adesired one of multiple modes of electrolarynx operation. In addition,the “nonlinear frequency characteristic aspect” of the present inventionimproves upon the foregoing by providing a nonlinear relationshipbetween force on the pushbutton (i.e., force on the PSR) and frequencyof the electrolarynx tone in order to thereby improve frequency controlat the low end of the pushbutton-controlled frequency range.

To paraphrase some of the more precise language developed herein for themode switch aspect of the present invention, an electrolarynxconstructed according to the mode switch aspect of the present inventionincludes an enhanced, multimode pushbutton-PSR arrangement. Theelectrolarynx includes (i) a case, (ii) tone-producing circuitry on thecase for producing an electrolarynx tone having a frequency and avolume, (iii) a power switch on the case for turning on power to thetone-producing circuitry, (iv) a pushbutton on the case that isoperatively connected to the power switch for purposes of enabling auser to activate the power switch, and (v) a PSR physically coupled tothe pushbutton so that the PSR resistor has a resistance value dependenton the pressure a user applies to the pushbutton.

According to the mode switch aspect invention, the tone-producingcircuitry is configured to operate in multiple user-selected modes ofelectrolarynx operation. In a first frequency-varying mode (i.e., afirst FVM), the tone-producing circuitry varies the frequency of theelectrolarynx tone according to variations in the PSR resistance value.In a first volume-varying mode (i.e., a first VVM), the tone-producingcircuitry varies the volume. A mode switch component of theelectrolarynx enables the user to set a user-selected mode of operation.Preferably, additional modes of operation are included, some of whichvary sensitivity to changes in the PSR resistance value.

According to the nonlinear frequency characteristic aspect of thepresent invention, the tone-producing circuitry varies thepushbutton-controlled frequency of the electrolarynx tone as a nonlinearfunction of the force applied to the pushbutton (i.e., a nonlinearfunction of the PSR resistance value). Less sensitivity to applied forceat the low end of the pushbutton-controlled frequency range results,thereby facilitating low frequency adjustments by a user who is onlylightly pressing the pushbutton.

Thus, the present invention provides an electrolarynx having significantimprovements and increase functionality, including ease of bothfrequency and volume variation using a single pushbutton-PSRcombination, and a nonlinear frequency characteristic that is achieved,in one form of the invention, with a shaping factor saved in alogarithmic lookup table. The following illustrative drawings anddetailed description make the foregoing and other objectives, features,and advantages of the invention more apparent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 of the drawings is a first perspective view of an electrolarynxconstructed according to the mode switch aspect of the invention,showing the distal or forward end portion of the electrolarynxpositioned toward the top of the drawing sheet, a pushbutton sideportion (i.e., a control-button side portion) positioned toward the leftside of the drawing sheet, and a proximal portion (i.e., a bottomportion) positioned toward the bottom of the drawing sheet;

FIG. 2 of the drawings is a second perspective view of theelectrolarynx, showing the distal end portion positioned toward theright side of the drawing sheet, the pushbutton side portion positionedtoward the bottom of the drawing sheet, and the proximal end portionpositioned toward the right side of the drawing sheet;

FIG. 3 of the drawings is a third perspective view of the electrolarynx,with the bottom end cap removed so that the mode switch is visible, asviewed facing toward the proximal end portion of the electrolarynx;

FIG. 4 is a diagrammatic block diagram of the electrolarynxtone-producing circuitry, including the pushbutton, the PSR, and themode switch;

FIG. 5 is a schematic diagram showing connections to a microcontrollercomponent of the tone-producing circuitry;

FIG. 6 is a hybrid block-diagram-flow-chart depiction of frequencycontrol as accomplished according to the nonlinear frequencycharacteristic aspect of the invention;

FIG. 7 is a sample Equation 1 for calculating shaping factors for thedesired nonlinear frequency characteristics; and

FIG. 8 is a “Table A” that provides sample “button pressure versus tonefrequency” data for both linear and nonlinear frequency characteristics.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description proceeds by describing the mode switch aspectof the present invention in a first section entitled “Mode Switch.” Thedescription continues thereafter by describing the nonlinear frequencycharacteristic aspect in a second section entitled “Nonlinear FrequencyCharacteristic.” A reader of this description who is already familiarwith the mode switch description of the present invention may choose toproceed directly to the “Nonlinear Frequency Characteristic” section.

Mode Switch.

FIGS. 1, 2, and 3 of the drawings show an electrolarynx 10 constructedaccording to the mode switch aspect of the present invention. Theelectrolarynx 10 may be similar in many respects to the electrolarynxesdescribed in U.S. Pat. Nos. 5,812,681; 6,252,966; 9,031,249; and9,116,539. Those patents are incorporated herein in their entireties bythis reference for all the information they provide.

Generally, the electrolarynx 10 includes a case 11 (FIGS. 1, 2, and 3)that extends along a central axis of elongation 12 of the case 11,between a first or bottom end cap 13 at a proximal or bottom end portionof the case (FIGS. 1 and 2) and a second or top end cap at a distal orforward end portion of the case (FIGS. 1 and 2). The user grasps thecase 11, presses the top end cap 14 (i.e., the sound-producingtransducer portion at the forward end of the electrolarynx 10) againstthe outside of their throat in order to introduce an electrolarynx toneto their mouth and throat, and then modulates that tone by holding theirbreath while varying the shape of the resonant speech cavity and makingthe usual tongue, teeth, and lip constrictions so as to articulate themodulated tone as human speech.

The case 11 is a handheld component (e.g., a molded-plastic or metalalloy object) having an overall length of about four to five inchesmeasured along the central axis of elongation 12. Of course, thatdimension provides an idea of the size of the various components of theillustrated embodiment; the size may vary without departing from theinventive concepts described herein. The case 11 includes a firstlongitudinally extending section (i.e., a first half) and a secondlongitudinally extending section (i.e., a second half) that, when fullyassembled, are held together by the bottom and top end caps 13 and 14.The assembler person screws the bottom and top end caps 13 and 14 ontothe first and second sections, in threaded engagement of the first andsecond sections, to hold the two halves together. Thus, the term “case”herein means an object such as the case 11, an object that is preferablyno longer than about seven inches, with a cross sectional area that ispreferably no more than about five to seven square inches.

With the first and second sections fully assembled, the case 11 definesa hollow interior that provides a space for a battery-powered circuitboard 15 that is the combination of a first circuit board section 15Aand a second circuit board section 15B (FIG. 2). Circuitry on and/orconnected to the circuit board 15 includes a switch-activatingpushbutton 16 (i.e., a switch-depressing component) that is identifiedin FIGS. 1 through 5, a mode switch 17 (FIGS. 2 through 5), afrequency-controlling first thumbwheel 18 (FIGS. 2 and 4), and avolume-controlling thumbwheel 19 (FIGS. 1, 3, and 4). The user depressesthe pushbutton 16 to turn on power to the electrolarynx 10 so that itproduces an electrolarynx tone, while the user operates the thumbwheels18 and 19 to set a desired frequency and volume of that tone.

FIG. 4 shows the components mentioned above, together with additionalcomponents of the electrolarynx 10 that are connected to electroniccircuitry identified as “tone-producing circuitry 20.” Thetone-producing circuitry 20 includes a transducer component forproducing the electrolarynx tone. It may take the form of a known typeof electro-mechanical transducer assembly that includes a coil of magnetwire for producing a magnetic field such that it causes a plunger tovibrate against a button-like diaphragm and thereby produce a buzzingelectrolarynx sound (i.e., the electrolarynx tone) having an audiblefundamental frequency in the speech range of the average human voice(e.g., about 40 Hertz up to about 200 Hertz). Use of a linear motorfalls within the broader inventive concepts and the term transducercomponent herein includes that alternative.

The frequency-controlling first thumbwheel 18 is connected to a firstvariable resistor 18A that is, in turn, connected to the tone-producingcircuitry 20. Similarly, the volume-controlling second thumbwheel 19 isconnected to a second variable resistor 19A that is connected to thetone-producing circuitry 20. In operation, the action of the userdepressing the pushbutton 16 (e.g., a 0.4-inch diameter pushbutton)activates the switch 21 (i.e., turns on power) with the result that thetone-producing circuitry 20 produces the electrolarynx tone with athumbwheel-determined value of frequency (TWDF) andthumbwheel-determined level of volume (TWDV) that are determined by thepositions of the first and second thumbwheels 18 and 19.

According to the mode switch aspect of the present invention, thetone-producing circuitry 20 is configured to operate in multiple modesof electrolarynx operation. In a first frequency-varying mode (i.e., thefirst FVM), the tone-producing circuitry 20 enables the user to vary thefrequency of the electrolarynx tone from the TWDF within a range ofpushbutton-controlled frequencies that is predetermined or indicated byuser-inputted settings, doing so by varying pressure on the pushbutton16 (e.g., similar to the technique described in U.S. Pat. No.5,812,681). In the first volume-varying mode (i.e., the first VVM), thetone-producing circuitry 20 enables the user to vary the volume of theelectrolarynx volume from the TWDV by varying pressure on the pushbutton16. The user can preselect the first FVM or the first VVM using the modeswitch 17 component of the electrolarynx circuitry.

More specifically, the electrolarynx 10 includes a pressure-sensitiveresistor (i.e., a PSR 22 in FIG. 4) that is physically coupled to thepushbutton 16 (e.g., interposed between the pushbutton 16 and the switch21) so that the pressure-sensitive resistor has a resistance value thatis dependent on pressure applied by the user to the pushbutton 16. Theillustrated pushbutton 16 extends from a user-accessible position on theexterior of the case 11, through the case 11 to the interior of the case11, where it is mechanically coupled via the PSR 22 to the switch 21.The PSR 22 is a known type of component having a resistance value thatvaries according to the pressure applied to it; it is commerciallyavailable from various sources, including Interlink Electronics, Inc. ofCamarillo, Calif., and the term “pressure-sensitive resistor” herein(and the acronym “PSR”) mean a resistance component having a resistancevalue that varies according to the pressure (i.e., the force) applied tothat resistor component. Depressing the pushbutton 16 results inpressure against the PSR 22 that varies its resistance. Thus, the usercan depress the pushbutton 16 to turn on the electrolarynx tone, andalso to vary the resistance of the PSR 22. The tone-producing circuitry20 responds to variations in the resistance of the PSR 22 by varying thefrequency or volume of the electrolarynx tone according to the selectedmode of electrolarynx operation.

Preferably, additional modes are provided for also, including, forexample, a communications-link mode for enabling control from anexternal device, and a disabled mode for disabling response of thetone-producing circuitry 20 to the PSR 22. Moreover, five or more modesmay be included. At initial power up of the electrolarynx 10 (e.g., byinserting a nine-volt battery), the tone-producing circuitry 20preferably defaults to the disabled mode mentioned above. Preferably, amode selected after initial power up is maintained in memory duringperiods that the electrolarynx 10 is not in use.

The mode switch 17 of the electrolarynx 10 enables a user to select adesired one of multiple modes of operation. The illustrated mode switch17 is a momentary, normally open, pushbutton switch that the useroperates for that purpose, with the tone-producing circuitry 20responding to each operation of the mode switch 17 by stepping throughmultiple modes of operation. Other types of user input devices may beused for mode control instead within the broader inventive conceptsdescribed herein. For the illustrated mode switch 17, the user depressesit one time to select the first FVM and multiple times to select thefirst VVM.

The tone-producing circuitry 20 in FIG. 4 is configured so that theelectrolarynx 10 operates as herein described. In other words, thetone-producing circuitry 20 includes a combination of analog and/ordigital circuit components that are interconnected (and programmed whererequired) to work together and function as stated. FIG. 5 shows thetone-producing circuitry 20 implemented with a microcontroller 30 thatcontrols operation under program control to provide a transducercomponent drive signal at a line 31 in FIG. 5 that results in theelectrolarynx tone. The illustrated microcontroller 30 is, for example,the flash microcontroller having part number PIC16F1824 that isavailable from Microchip Technology Inc. of Mission Viejo, Calif., andthe term “microcontroller” herein means a small electronic computerdevice (e.g., an integrated circuit containing a processor core andmemory) that operates under program control according to the way it hasbeen programmed. The microcontroller 30 is accompanied by suitablesupport circuitry, including a battery connected to the plus (+) andminus (−) terminals in FIG. 5. It is programmed to function as hereindescribed (e.g., in line with known programming techniques). A USB port40 (FIG. 4) facilitates communication with the microcontroller 30.Suitable programming for the microcontroller may be created by aprogrammer in any of various known ways to implement the presentinvention, including, for example, using a high-level, general purposeprogramming language (e.g., the commonly used “C” programming language)to produce a source program with the desired features that theprogrammer compiles and converts to a machine language program file fora manufacturer of the microcontroller to use in loading the programmingonto the microcontroller as part of the manufacturing process.

Preferably, the tone-producing circuitry 20 of the electrolarynx 10 isconfigured to enable the user to set a user-selected one of multiplesensitivity levels for the FVM and VVM operational modes of theelectrolarynx 10. In other words, the tone-producing circuitry 20 isconfigured to respond to variations in PSR resistance with a degree ofsensitivity to PSR resistance that the user sets with the mode switch.Depressing the mode button one (1) time after initially powering up theelectrolarynx 20, for example, results in the first FVM at a first or“low” FVM sensitivity level (i.e., changes in frequency are relativelyless sensitive to variations in PSR resistance). Similarly, depressingthe mode button two (2) times results in a second FVM at a second or“low-medium” FVM sensitivity level, depressing it three (3) timesresults in a third FVM at a third or “high-medium” FVM sensitivitylevel, and depressing it four (4) times results in a fourth FVM at afourth or “high” FVM sensitivity level.

For multiple volume-varying modes, depressing the mode button five (5)times results in the first VVM at a first or “low” VVM sensitivitylevel, and depressing the mode button six (6) times results in a secondVVM at a second or “high” VVM sensitivity level. After that, depressingthe mode button seven (7) times results in the communications-link modeof electrolarynx operation (i.e., control by an external device via thecommunications link), and depressing the mode button eight (8) timesresults in the disabled mode (i.e., the other modes of electrolarynxoperation are disabled). For additional depressions of the mode switch,the tone-producing circuitry 20 recycles though the operational modesdescribed above for the mode-switch depressions one through eight, doingit that way until the next initial power-up of the electrolarynx (e.g.,battery change), at which time it begins anew as described above for thefirst mode-switch depression after initial power-on. One alternateembodiment of an electrolarynx constructed according to the invention,however, stores user settings in non-volatile memory so that they areretained for the next power-up of the electrolarynx.

The following summarizes some of the nomenclature used herein for thevarious frequency-varying and volume-varying modes:

-   -   1. The “first frequency-varying mode” is a first FVM in which        the tone-producing circuitry varies the frequency of the        electrolarynx tone according to variations in the resistance        value of the pressure-sensitive resistor, doing so at a first        FVM sensitivity to the resistance value of the        pressure-sensitive resistor (e.g., a “low” FVM sensitivity        level).    -   2. The “second frequency-varying mode” is a second FVM in which        the tone-producing circuitry varies the frequency of the        electrolarynx tone according to variations in the resistance        value of the pressure-sensitive resistor, doing so at a second        FVM sensitivity to the resistance value of the        pressure-sensitive resistor (e.g., a “low-medium” FVM        sensitivity level).    -   3. The “third frequency-varying mode” is a third FVM in which        the tone-producing circuitry varies the frequency of the        electrolarynx tone according to variations in the resistance        value of the pressure-sensitive resistor, doing so at a third        FVM sensitivity to the resistance value of the        pressure-sensitive resistor (e.g., a “high-medium” FVM        sensitivity level).    -   5. The “fourth frequency-varying mode” is a fourth FVM in which        the tone-producing circuitry varies the frequency of the        electrolarynx tone according to variations in the resistance        value of the pressure-sensitive resistor, doing so at a fourth        FVM sensitivity to the resistance value of the        pressure-sensitive resistor (e.g., a “high” FVM sensitivity        level).    -   6. The “first volume-varying mode” is a first VVM in which the        tone-producing circuitry varies the volume of the electrolarynx        tone according to variations in the resistance value of the        pressure-sensitive resistor, doing so at a first        volume-varying-mode (VVM) sensitivity to the resistance value of        the pressure-sensitive resistor (e.g., a “low” VVM sensitivity        level).    -   7. The “second volume-varying mode” is a second VVM in which the        tone-producing circuitry varies the volume of the electrolarynx        tone according to variations in the resistance value of the        pressure-sensitive resistor, doing so at a second VVM        sensitivity to the resistance value of the pressure-sensitive        resistor (e.g., a “high” VVM sensitivity level).

Concerning the communications-link mode of electrolarynx operation, theelectrolarynx 10 includes communication circuitry 50 for that purpose(FIG. 4). It communicates, for example, with an external device (notshown) that is not physically connected to the electrolarynx 10. Thecommunication circuitry 50 is connected to the tone-producing circuitry20 and may use known technology, including, for example, 2.45 GHz radiofrequency (RF) communications and/or an infrared (IR) receiver.Frequency and/or volume information are communicated from the externaldevice via the circuitry 50.

From the descriptions provided and those incorporated by reference, aperson having ordinary skill in the art (i.e., a PHOSITA) can readilyprovide suitable circuitry for the communication link. Any of varioustransmission, reception, and encoding methods may be used, includingwire, radio, and infrared. The illustrated communications circuitry 50may include, for example, an infrared sensor (not shown) that extendsthrough an opening in the case 11 where it receives an infrared signalon which at least one of “on-off information,” “frequency information,”and “volume information” is encoded. That information is encoded at theexternal device, for example, in response to a pressure sensor placedproximate an opening in the user's throat through which the user exhales(e.g., a surgical opening called a stoma).

Thus, the mode switch aspect of the present invention provides anelectrolarynx having a pushbutton for turning on the electrolarynx tone,a PSR coupled to the pushbutton, tone-producing circuitry for producingvariations in attributes of the electrolarynx tone according tovariations in the resistance of the PSR, and a mode switch for enablinga user to select the tone attributes affected. Although an exemplaryembodiment has been shown and described, one of ordinary skill in theart may make many changes, modifications, and substitutions withoutnecessarily departing from the spirit and scope of the invention. Thespecific terminology used to describe the exemplary embodiment is notintended to limit the invention; each specific term is intended toinclude all technical equivalents that operate in a similar manner toaccomplish a similar purpose or function.

Nonlinear Frequency Characteristic.

Having described the mode switch aspect of the present invention, thisdescription now turns to the nonlinear frequency characteristic aspect.It improves upon the mode switch aspect by providing a nonlinearfrequency characteristic relating force on the pushbutton (i.e., the PSRresistance value) to the frequency of the electrolarynx tone. Thatnonlinear characteristic is accomplished in one embodiment of thepresent invention by configuring the tone-producing circuitry so that itapplies a shape factor (e.g., a shape factor K) to linearly derivedfrequency values.

FIG. 6 provides a diagram 60 as an example of the overall methodologyinvolved in producing a nonlinear frequency characteristic according tothe present invention. The manner in which that is accomplished relieson the microcontroller 30 of the tone-producing circuitry; it has beenprogrammed to measure V_(IN) (i.e., the voltage on the node that isidentified in FIG. 5 as “Voltage Node 1”) as the current value of V_(IN)and to set the current frequency of the electrolarynx tone according tothe current value of V_(IN).

The measurement of V_(IN) is made with the analog-to-digital converter(ADC) of the microcontroller 30. As indicated at a block 61 in FIG. 6,the microcontroller 30 of the tone-producing circuitry is programmed todetermine V_(IN) for zero force on the PSR 22 (i.e., when the user isnot applying force to the pushbutton 16). That value is referred toherein as V₀ (i.e., the letter “V” with a subscript “0”). Themicrocontroller 30 is also programmed to determine V_(IN) for full forceon the PSR 22 (i.e., when the user is pushing the pushbutton 16 to afully depressed position of the pushbutton 16). That value is referredto herein as V₁₆ (i.e., the letter “V” with a subscript “16”).

Having determined V₀ and V₁₆, the microcontroller 30 of the illustratedembodiment builds a table of conversion values, including shape factorsK, as indicated at a block 62 in FIG. 6. That is done (in the exampleillustrated by the diagram 60) for a progression of seventeen incrementsof force on the PSR 22. In doing so, the microcontroller 30 calculates alinear, uniformly spaced apart (i.e., increasing in value uniformly)progression of fifteen values of V_(IN) lying between the valuesdetermined in the block 61 for V₀ and V₁₆. Those fifteen values arereferred to hereinafter as V₁ (i.e., the letter “V” with a subscript“1”) through V₁₅ (i.e., the letter “V” with a subscript “15”), with eachof the resulting valves of V₀ through V₁₆ corresponding to a respectiveone of the seventeen increments of force on the PSR 22 (referred tohereinafter as P₀ through P₁₆).

In building the table of values, the microcontroller 30 calculates anadjusted value of voltage for each value of V_(IN). Those adjustedvalues are referred to herein as V_(ADJ) (i.e., the letter “V” with asubscript “ADJ”). The value of V_(ADJ) corresponding to each value ofV_(IN) (i.e., for each of V₀ through V₁₆) is calculated to be V_(IN)reduced by the value V₀, with the result that the values of V_(ADJ)range from zero (corresponding to V₀) to the value of V₁₆ reduced by thevalue of V₀ (corresponding to V₁₆). The microcontroller 30 is programmedto use a current voltage (V_(ADJ)) appearing across thepressure-sensitive resistor as an indication of a current resistancevalue of the pressure-sensitive resistor. Based upon the foregoing, themicrocontroller 30 completes the table of conversion values, withseventeen shape factors K (i.e., K₀ through K₁₆), and stores them inmemory for use in real time conversion to a nonlinear frequencycharacteristic. In other words, the microcontroller is programmed todetermine the shape factors (K), each of which corresponds to arespective one of a plurality of incremental increases in the resistancevalue (i.e., increases that correspond to the seventeen increments offorce (P₀ through P₁₆) on the PSR 22.

Instead of building and storing a table of conversion values, however, aperson having ordinary skill in the art can, based upon the descriptionprovided herein, readily program the microcontroller 30 to compute tablevalues at the time they are needed (e.g., periodically or whenever achange in V_(IN) occurs). The example illustrated in the diagram 60,however, uses a table of values that is stored in the memory of themicrocontroller 30. As indicated at a block 63 in FIG. 6, themicrocontroller 30 proceeds to monitor the value of V_(IN). As changesin V_(IN) occur, the microcontroller 30 changes the electrolarynx tonefrequency accordingly (as indicated at a block 64) using shape factors Kto result in a nonlinear frequency characteristic relative to the forceon the PSR 22. After setting the frequency that way to reflect thecurrent value of V_(IN), the microcontroller 30 continues to monitorV_(IN), as indicated by the return arrow to the block 63.

The Equation 1 in FIG. 7 provides an example of how the microcontroller30 computes the shape factors K (i.e., shape factors K₀ through K₁₆) forthe illustrated embodiment of the present invention. As indicated byEquation 1, the shape factor K (expressed as a percentage value) iscalculated, for each of the seventeen increments of force on the PSR 22(i.e., P₀ through P₁₆), to be equal to the product of one hundred (100)and the illustrated ratio. The letter “X” in that ratio represents oneof the seventeen pushbutton pressure increments (i.e., P₀ through P₁₆)that correspond to respective ones of the seventeen values of V_(IN)(i.e., V₀ through V₁₆). The “Scale” parameter in that ratio represents adesired amount of nonlinearity.

Any of various shape factors may be used to achieve a desired nonlinearfrequency characteristic within the broader inventive concepts of thepresent invention, and such shape factors may be determined bycalculating them using a suitable equation or by setting themempirically, or otherwise. Equation 1, however, gives a reasonableapproximation to a logarithmic curve, and the Scale parameter can beused to set the direction and depth of the resulting curve. Setting theScale parameter to zero (i.e., Scale=0) results in a straight line;setting it greater than zero (i.e., Scale>0) results in a curve that isshallow at low values (less sensitivity to changes in force on PSR 22)and steep at high values; setting it less than zero (i.e., Scale<0)result in a curve that is steep at low values (greater sensitivity tochanges in force on the PSR 22) and shallow at high values.

FIG. 8 illustrates the Table A as an example of a table of values havingseventeen values of shape factor K in the column headed with “ShapeFactor K” (i.e., K₀=0.00% through K₁₆=100.00% corresponding to P₀through P₁₆). The microcontroller 30 determined those values of shapefactor K using Equation 1 with a Scale parameter greater than zero(i.e., Scale>0). Table A also includes table values of V_(IN)corresponding to P₀ through P₁₆ in a column headed “ADC Voltage V_(IN)”(i.e., V₀=1.65 through V₁₆=3.30), along with table values of V_(ADJ)corresponding to P₀ through P₁₆ in a column headed “ADC Voltage V_(IN)”(i.e., 0.00 volts through 1.65 volts). In addition, Table A presentstable values of F_(L) (i.e., the frequencies for a linear frequencycharacteristic over a pushbutton-controlled frequency range of 50.00Hertz to 150.00 Hertz that is predetermined or specified by usersettings), each such table value corresponding to a respective one of P₀through P₁₆. Table A also presents corresponding table values of V_(K)(i.e., the shaped voltage reflecting the shape factor K applied to thecorresponding value of V_(ADJ)), and corresponding table values of F_(K)(the shaped frequency reflecting the shape factor K applied to thecorresponding value of F_(L)).

In determining values as shown in Table A, the microcontroller 30 firstuses the ADC to determined V_(IN) corresponding to P₀ (i.e., V₀=1.65volts) and V_(IN) corresponding to P₁₆ (i.e., V₁₆=3.30 volts). Usingthose values for V₀ and V₁₆, the microcontroller 30 determines theremaining fifteen values of V₂ through V₁₅ in order to produce linearprogression of seventeen values of V_(IN) (i.e., V₀ through V₁₆). Next,the microcontroller determines the illustrated seventeen values ofV_(ADJ) (e.g., the 0.00 volts through 1.65 volts shown in Table A),doing so by reducing the values of V₀ through V₁₅ by the 1.65-volt valueof V_(IN) to produce a linear progression of seventeen values ofV_(ADJ). Having determined those values, the microcontroller 30 sets thecurrent frequency of the electrolarynx tone according to the currentvalue of V_(IN) by applying the corresponding shape factor K to thecorresponding value of F_(L), interpolating values where appropriate(e.g., straight line interpolation).

As an example of setting the current frequency in line with the presentinvention using the values presented in Table A, suppose that thecurrent value of V_(IN) at the Voltage Node 1 identified in FIG. 5 isdetermined by the ADC to be 2.0 volts (i.e., a value between the V₃=1.96table value of V_(IN) corresponding to P₃ and the V₄=2.06 table value ofV_(IN) corresponding to P₄). The microcontroller 30 first reduces thatcurrent 2.0-volt value of V_(IN) by 1.65 volts to a value of 0.35 voltsas the adjusted current value of V_(ADJ), and then proceeds to set thecurrent frequency F_(K) accordingly.

Inasmuch as the 0.35-volt adjusted current value of V_(ADJ) lies betweenthe 0.31-volt table value of V_(ADJ) corresponding to P₃ and the0.41-volt table value of V_(ADJ) corresponding to P₄, themicrocontroller 30 interpolates between the 0.50% table value of theshape factor K corresponding to P₃ and the 1.25% table value of theshape factor K corresponding to P₄ accordingly (e.g., a linearinterpolation) to give a currently operative shape factor K of 0.80%.Applying that 0.80% interpolated shape factor to the 0.35-volt adjustedcurrent value of V_(ADJ) (i.e., applied by multiplying 0.35 by 0.008)yields a 0.0028-volt current value of the shaped voltage V_(K)(corresponding to the current 2.0-volt value of V_(IN)). Similarly, alinear interpolation between the 50.19-Hertz table value of F_(K)corresponding to P₃ and the 50.62-Hertz table value of F_(K)corresponding to P₄ gives a 50.36-Hertz interpolated value for thecurrent shaped frequency of the electrolarynx tone (corresponding to thecurrent 2.0-volt value of V_(IN)). In other words, the microcontroller30 is programmed to interpolate between two shape factors (K) in orderto produce an intermediate shape factor. The tone-producing circuitry 20(FIG. 4) with its microcontroller 30 then produces the electrolarynxtone as predetermined for the current value of the shaped frequency sodetermined, doing so in line with the above explanation.

Summarizing the nonlinear frequency characteristic aspect of the presentinvention, the tone-producing circuitry 20 varies thepushbutton-controlled frequency of the electrolarynx tone as a nonlinearfunction of the force applied to the pushbutton 16 (i.e., a nonlinearfunction of the PSR 22 resistance value). The microcontroller 30 ispreferably programmed to accomplish that result as provided for by thetable values in Table A, so that less sensitivity to applied forceresults at the low end of the pushbutton-controlled frequency range,thereby facilitating low frequency adjustments by a user when the useris only lightly pressing the pushbutton 16. In other words, themicrocontroller component of the tone-producing circuitry is programmedto vary the frequency of the electrolarynx tone so that the frequency ofthe electrolarynx tone is related to the resistance value of PSR 22 by anonlinear function, preferably over the entire pushbutton-controlledfrequency range, and the illustrated embodiment does so to result inreduced sensitivity to the force a user applies to the pushbutton 16 atthe low end of the pushbutton-controlled frequency range.

Of course, it is not necessary to fully populate a table of values suchas the Table A in order to implement the present invention. Theillustrated full Table A is simply provided as an aid in explaining themethodology of the present invention. A programmer may, instead, simplystore in memory, or program the microcontroller to calculate, variousvalues of the shape factor K that provide a desired nonlinear frequencycharacteristic. Depending on the capabilities of the microcontrollerused, and inasmuch as the maximum and minimum values of V_(IN) and F_(L)are known parameters (or readily ascertained), a current value of thelinear frequency F_(L) (i.e., the instantaneous value of F_(L)) may becalculated in real time as a function of the current value of the ADCvoltage V_(IN) (i.e., the instantaneous value of V_(IN)) and those knownparameters (e.g., a continuous function over the range of the voltageV_(IN)). Moreover, the shape factor K to be applied to the current orinstantaneous value of F_(L) (in order to yield the current orinstantaneous value of the shaped frequency F_(K)) may be calculated inreal time also (e.g., as a continuous function over the range of F_(L)).

Stated another way, the microcontroller 30 is programmed to determine acurrent value of frequency (F_(K)) as a function of a current voltage(V_(ADJ)) appearing across the pressure-sensitive resistor, and todetermine a current shape factor (K) as a function of the currentvoltage (V_(ADJ)). In other words, the microcontroller 30 is programmedto determine a current frequency (F_(L)) of a linear frequencycharacteristic relating frequency to the resistance value of thepressure-sensitive resistor, and to apply a shape factor (K) to saidcurrent frequency (F_(L)) in order to determine a current frequency(F_(K)) of a nonlinear frequency characteristic relating frequency tothe resistance value of the pressure-sensitive resistor.

Based upon the foregoing description and claims herein, one of ordinaryskill in the art can readily implement the present invention with manychanges, modifications, and substitutions to the illustrated embodimentwithout necessarily departing from the spirit and scope of the presentinvention. The specific terminology used to describe the illustratedembodiment is not intended to limit the invention; each specific term isintended to include all technical equivalents that operate in a similarmanner to accomplish a similar purpose or function.

Battery Status.

One improvement to the electrolarynx described above relates to batterystatus. When using a standard alkaline or NiMH 9-volt battery, forexample, it is very easy to tell when the battery needs charging. Thevoltage drops as the battery gets weaker. For a 9-volt lithium battery,however, the voltage drop is less noticeable, and when the battery hitsa “dead” status (i.e., charge fully depleted), the battery suddenly cutsout without warning. Or, for a smaller voltage battery (e.g., AA batteryor batteries, or a single cell lithium battery at 3.7 volts) incombination with a voltage step-up circuit, the step-up circuit willmask the status of the battery that is nearly ready for charging. Someusers are very concerned that when using a lithium battery, they maylose their voice because the electrolarynx device just cuts out withoutwarning. So, the user will often charge the battery far more often thanwas really necessary.

A solution to the above problem is achieved according to yet anotherinventive aspect by having the tone-producing circuitry (i.e., themicrocontroller) read battery voltage when the electrolarynx turns on,and then calculate battery “Charge Status.” A “charge-status”calculating chip may also be used to provide that data. If the ChargeStatus of the battery is below a certain threshold (e.g., 75% chargestatus, although that value may vary depending on requirements), thenthe “Maximum Volume” will be reduced (e.g., to 80% of normal maxvolume). When the microcontroller detects a low battery (i.e., theCharge Status is below said threshold), the “Full Volume” duty cyclewill become 15%, thus limiting how loud the electrolarynx tone is (i.e.under normal use, the duty cycle will be 20% at full volume). This givesthe user an audible warning that the battery requires charging, doing sobefore the electrolarynx just stops working. It also has the benefit ofextending the life of the battery, since the battery will not be drainedas fast. An alternate warning sound can be generated, such as rampingthe volume up over time (e.g., over about 500 milliseconds) so that theaudible warning is still there, but the Maximum Volume is stillmaintained.

What is claimed is:
 1. An electrolarynx, comprising: a case;tone-producing circuitry on the case for producing an electrolarynx tonehaving a frequency and a volume; a power switch on the case for turningon power to the tone-producing circuitry; a pushbutton on the case forenabling a user to activate the power switch; a pressure-sensitiveresistor on the case that is physically coupled to the pushbutton sothat the pressure-sensitive resistor has a resistance value such thatsaid resistance value is dependent on pressure applied by the user tothe pushbutton; and a microcontroller portion of the tone-producingcircuitry that is programmed to control the frequency of theelectrolarynx tone over a pushbutton-controlled range of frequenciesaccording to the resistance value of the pressure-sensitive resistor,said pushbutton-controlled range of frequencies extending from a minimumfrequency to a maximum frequency; wherein the microcontroller isprogrammed to vary the frequency of the electrolarynx tone between saidminimum frequency and said maximum frequency as a nonlinear function ofthe resistance value of the pressure-sensitive resistor; and wherein themicrocontroller is programmed to determine a current frequency (F_(L))of a linear frequency characteristic relating frequency to theresistance value of the pressure-sensitive resistor, and to apply ashape factor (K) to said current frequency (F_(L)) in order to determinea current frequency (F_(K)) of a nonlinear frequency characteristicrelating frequency to the resistance value of the pressure-sensitiveresistor.
 2. An electrolarynx as recited in claim 1, wherein themicrocontroller is programmed to vary the frequency of the electrolarynxtone according to the resistance value of the pressure-sensitiveresistor in order to achieve reduced sensitivity at and near the minimumfrequency.
 3. An electrolarynx as recited in claim 1, wherein themicrocontroller is programmed to determine a current voltage (V_(ADJ))appearing across the pressure-sensitive resistor as an indication of acurrent resistance value of the pressure-sensitive resistor.
 4. Anelectrolarynx as recited in claim 1, wherein the microcontroller isprogrammed to determine a plurality of shape factors (K), each of whichplurality of shape factors (K) corresponds to a respective one of aplurality of incremental increases in the resistance value of thepressure-sensitive resistor.
 5. An electrolarynx as recited in claim 4,wherein the microcontroller is programmed to interpolate between two ofsaid plurality of shape factors (K) in order to produce an intermediateshape factor.
 6. An electrolarynx as recited in claim 1, wherein themicrocontroller is programmed to determine a current value of frequency(F_(K)) as a function of a current voltage (V_(ADJ)) appearing acrossthe pressure-sensitive resistor.
 7. An electrolarynx as recited in claim1, wherein the microcontroller is programmed to determine a currentshape factor (K) as a function of a current voltage (V_(ADJ)) appearingacross the pressure-sensitive resistor.
 8. An electrolarynx comprising:a case; tone-producing circuitry on the case for producing anelectrolarynx tone having a frequency and a volume; a power switch onthe case for turning on power to the tone-producing circuitry; apushbutton on the case for enabling a user to activate the power switch;a pressure-sensitive resistor on the case that is physically coupled tothe pushbutton so that the pressure-sensitive resistor has a resistancevalue such that said resistance value is dependent on pressure appliedby the user to the pushbutton; and a microcontroller portion of thetone-producing circuitry that is programmed to control the frequency ofthe electrolarynx tone over a pushbutton-controlled range of frequenciesaccording to the resistance value of the pressure-sensitive resistor,said pushbutton-controlled range of frequencies extending from a minimumfrequency to a maximum frequency; wherein the microcontroller isprogrammed to vary the frequency of the electrolarynx tone between saidminimum frequency and said maximum frequency as a nonlinear function ofthe resistance value of the pressure-sensitive resistor; wherein theelectrolarynx includes a mode switch on the case that is electricallyconnected to the tone-producing circuitry; wherein the tone-producingcircuitry is configured to operate in a first frequency-varying mode inwhich the tone-producing circuitry varies the frequency of theelectrolarynx tone according to variations in the resistance value ofthe pressure-sensitive resistor, doing so at a first frequency-varyingmode sensitivity to the resistance value of the pressure-sensitiveresistor; wherein the tone-producing circuitry is configured to operatein a first volume-varying mode in which the tone-producing circuitryvaries the volume of the electrolarynx tone according to variations inthe resistance value of the pressure-sensitive resistor, doing so at afirst volume-varying mode sensitivity to the resistance value of thepressure-sensitive resistor; and wherein the tone-producing circuitry isconfigured to enable a user to select a desired mode of electrolarynxoperation by operation of the mode switch.
 9. An electrolarynx,comprising: a case; tone-producing circuitry on the case for producingan electrolarynx tone having a frequency and a volume; a power switch onthe case for turning on power to the tone-producing circuitry; apushbutton on the case for enabling a user to activate the power switch;a pressure-sensitive-resistor on the case that is physically coupled tothe pushbutton so that the pressure-sensitive resistor has a resistancevalue such that said resistance value is dependent on pressure appliedby the user to the pushbutton; and a mode switch on the case that iselectrically connected to the tone-producing circuitry; wherein thetone-producing circuitry is configured to operate in a firstfrequency-varying mode in which the tone-producing circuitry varies thefrequency of the electrolarynx tone according to variations in theresistance value of the pressure-sensitive resistor, doing so at a firstfrequency-varying mode sensitivity to the resistance value of thepressure-sensitive resistor; wherein the tone-producing circuitry isconfigured to operate in a first volume-varying mode in which thetone-producing circuitry varies the volume of the electrolarynx toneaccording to variations in the resistance value of thepressure-sensitive resistor, doing so at a first volume-varying modesensitivity to the resistance value of the pressure-sensitive resistor;wherein the tone-producing circuitry is configured to enable a user toselect a desired mode of electrolarynx operation by operation of themode switch; wherein the electrolarynx includes a microcontrollerportion of the tone-producing circuitry that is programmed to controlthe frequency of the electrolarynx tone according to the resistancevalue of the pressure-sensitive resistor; and wherein themicrocontroller is programmed to vary the frequency of the electrolarynxtone as a nonlinear function of the resistance value of thepressure-sensitive resistor.
 10. An electrolarynx, as recited in claim9, wherein: the electrolarynx includes communications circuitry forproviding a communications link with a device that is not physicallyconnected to the electrolarynx; the tone-producing circuitry isconfigured to operate in a communications-link mode in which thetone-producing circuitry responds to control information received viathe communications link; and wherein the tone-producing circuitry isconfigured to enable a user to select the communications-link mode byoperation of the mode switch.
 11. An electrolarynx, as recited in claim9, wherein: the tone-producing circuitry is configured to operate in adisabled mode in which the frequency-varying mode, the volume-varyingmode, and the communications-link mode are disabled; and wherein thetone-producing circuitry is configured to enable a user to select thedisabled mode by operation of the mode switch.
 12. An electrolarynx, asrecited in claim 9, wherein: the tone-producing circuitry is configuredto operate in multiple modes of electrolarynx operation; and thetone-producing circuitry is configured to respond to a predeterminednumber of mode switch closures in setting a corresponding user-selectedmode of electrolarynx operation.
 13. An electrolarynx, as recited inclaim 9, wherein the tone-producing circuitry is configured to operatein multiple frequency-varying modes such that each of said multiplefrequency-varying modes has a different frequency-varying modesensitivity to the resistance value of the pressure-sensitive resistor;and the tone-producing circuitry is configured to operate in auser-selected one of said multiple frequency-varying modes according tooperation of the mode switch.
 14. An electrolarynx, as recited in claim9, wherein the tone-producing circuitry is configured to operate inmultiple volume-varying modes such that each of said multiplevolume-varying modes has a different volume-varying mode sensitivity tothe resistance value of the pressure-sensitive resistor; and thetone-producing circuitry is configured to operate in a user-selected oneof said multiple volume-varying modes according to operation of the modeswitch.
 15. An electrolarynx, as recited in claim 9, wherein thetone-producing circuitry is configured to operate in multiple modes ofelectrolarynx operation according to operation of the mode switch sothat (1) a first closure of the mode switch sets the firstfrequency-varying mode at the first frequency-varying mode sensitivity,(2) a second closure of the mode switch sets a second frequency-varyingmode at a second frequency-varying mode sensitivity, (3) a third closureof the mode switch sets a third frequency-varying mode at a thirdfrequency-varying mode sensitivity, (4) a fourth closure of the modeswitch sets a fourth frequency-varying mode at a fourthfrequency-varying mode sensitivity, (5) a fifth closure of the modeswitch sets the first volume-varying mode at the first volume-varyingmode sensitivity (6) a sixth closure of the mode switch sets a secondvolume-varying mode at a second volume-varying mode sensitivity, (7) aseventh closure of the mode switch sets the communications-link mode,and (8) an eighth closure of the mode switch sets the disabled mode. 16.An electrolarynx, as recited in claim 9, wherein: the electrolarynxincludes a battery that provides power to the tone-producing circuitry;the tone-producing circuitry is configured to produce the electrolarynxtone at various volume levels up to a Maximum Volume; the tone-producingcircuitry is configured to calculate a Charge Status of the battery; andthe tone-producing circuitry is configured to reduce the level of theMaximum Volume according to the Charge Status of the battery.
 17. Anelectrolarynx, as recited in claim 16, wherein the tone-producingcircuitry is configured to produce a warning sound if the battery ChargeStatus of the battery falls below a predetermined level.